Objective: 

Given the importance of inflammation in acute kidney injury and the relationship between vitamin D and inflammation, we sought to elucidate the effect of vitamin D on acute kidney injury. We hypothesized that deficiency in 25-hydroxyvitamin D prior to hospital admission would be associated with acute kidney injury in the critically ill.

Design: 

Two-center observational study of patients treated in medical and surgical intensive care units.

Setting: 

Two hundred nine medical and surgical intensive care beds in two teaching hospitals in Boston, Massachusetts.

Patients: 

Two thousand seventy-five patients, aged ≥18 yrs, in whom serum 25-hydroxyvitamin D was measured prior to hospitalization between 1998 and 2009.

Interventions: 

None.

Measurements and Main Results: 

The exposure of interest was preadmission serum 25-hydroxyvitamin D and categorized a priori as deficiency (25-hydroxyvitamin D <15 ng/mL), insufficiency (25-hydroxyvitamin D 15–30 ng/mL), or sufficiency (25-hydroxyvitamin D ≥30 ng/mL). The primary outcome was acute kidney injury defined as meeting Risk, Injury, Failure, Loss, and End-stage kidney disease (RIFLE) Injury or Failure criteria. Logistic regression examined the RIFLE criteria outcome. Adjusted odds ratios were estimated by multivariate logistic regression models. Preadmission 25-hydroxyvitamin D deficiency is predictive of acute kidney injury. Patients with 25-hydroxyvitamin D deficiency have an odds ratio for acute kidney injury of 1.73 (95% confidence interval 1.30–2.30; p < .0001) relative to patients with 25-hydroxyvitamin D sufficiency. 25-Hydroxyvitamin D deficiency remains a significant predictor of acute kidney injury following multivariable adjustment (adjusted odds ratio 1.50; 95% confidence interval 1.42–2.24; p < .0001). Patients with 25-hydroxyvitamin D insufficiency have an odds ratio for acute kidney injury of 1.49 (95% confidence interval 1.15–1.94; p = .003) and an adjusted odds ratio of 1.23 (95% confidence interval 1.12–1.72; p = .003) relative to patients with 25-hydroxyvitamin D sufficiency. In addition, preadmission 25-hydroxyvitamin D deficiency is predictive of mortality. Patients with 25-hydroxyvitamin D insufficiency have an odds ratio for 30-day mortality of 1.60 (95% confidence interval 1.18–2.17; p = .003) and an adjusted odds ratio of 1.61 (95% confidence interval 1.06–1.57; p = .004) relative to patients with 25-hydroxyvitamin D sufficiency.

Conclusion: 

Deficiency of 25-hydroxyvitamin D prior to hospital admission is a significant predictor of acute kidney injury and mortality in a critically ill patient population.